A method of managing an optical communications network comprising a plurality of nodes interconnected by optical sections. The method comprises: identifying one or more pairs of adjacent DL-equipped nodes at which dummy light (DL) hardware is deployed, respective dummy light (DL) hardware being deployed at fewer than the plurality of the nodes of the optical communications network, the respective DL hardware deployed at a particular node configured to supply dummy light to each optical section extending from the particular node, and defining a respective single-section DL path between each identified pair of adjacent DL-equipped nodes; identifying one or more pairs of non-adjacent DL-equipped nodes at which DL hardware is deployed, and defining a respective multi-section DL path between each identified pair of non-adjacent DL-equipped nodes; and causing the deployed DL hardware to supply DL light to each of the single- and the multi-section DL paths.

An optical circuit breaker includes a main optical transmission path including an optical coupler, a delay line and a protection device, and a parallel protection path configured to receive a tapped portion of a signal provided to the main optical transmission path and generate a reference signal based on the tapped portion. The protection device may be configured to be triggered to prevent an overpower condition from passing through the optical circuit breaker responsive to the reference signal exceeding a user selectable threshold. The delay line may be configured to have a longer delay than a time it takes for the protection device to be triggered via the parallel protection path.

A method for establishing bidirectional communication links includes: supplying, to at least two optical transceiver modules at each side of at least two optical paths, a multiplexed optical CW signal comprising at least two optical CW signals having the same differing wavelengths, and modulating the multiplexed optical CW signal according to modulation signals; creating, at each side of the optical paths, at least two first and second optical transmit signals by optically filtering the modulated optical signals so that only a single wavelength remains, and routing pairs of a first and second optical transmit signal to the optical paths, wherein the optical transmit signals of each pair have differing wavelengths and wherein the optical transmit signals transmitted in the same direction over the same optical paths have differing wavelengths; receiving each optical transmit signals at a dedicated optical transceiver module by mixing it with the multiplexed optical CW signal.

A procedure for transferring wavelengths, and a system that operates in accordance with the procedure. The system comprises at least one network terminal, each including a switch and a controller. A plurality of wavelength sets are applied to the switch. The controller is arranged to operate the switch such that the switch (a) selects at least one wavelength from at least one of the plurality of wavelength sets, based on electrical monitoring at a port module external to the network terminal, and (b) outputs the at least one wavelength to an output of the at least one network terminal.

A method for establishing bidirectional communication links includes: supplying, to at least two optical transceiver modules at each side of at least two optical paths, a multiplexed optical CW signal comprising at least two optical CW signals having the same differing wavelengths, and modulating the multiplexed optical CW signal according to modulation signals; creating, at each side of the optical paths, at least two first and second optical transmit signals by optically filtering the modulated optical signals so that only a single wavelength remains, and routing pairs of a first and second optical transmit signal to the optical paths, wherein the optical transmit signals of each pair have differing wavelengths and wherein the optical transmit signals transmitted in the same direction over the same optical paths have differing wavelengths; receiving each optical transmit signals at a dedicated optical transceiver module by mixing it with the multiplexed optical CW signal.

Embodiments of the invention disclose a communication method which includes: receiving, by the optical network unit (ONU) by using the first port or the second port, a wavelength switching request message delivered by the optical line terminal (OLT), where the wavelength switching request message carries second wavelength channel information and port information that is of the second port; switching, by the ONU, an operating wavelength channel of an optical module connected to the second port from a first wavelength channel to a second wavelength channel corresponding to the second wavelength channel information; and sending, by the ONU, a wavelength switching complete message to the OLT by using the first port. According to the communication method provided in embodiments of the present invention, quick wavelength switching is performed based on the second port, so that a service is not interrupted in a wavelength switching process, and user experience is better.

An optical switch, comprising: a first optical waveguide, a first optical add path, a second optical add path and a micro-ring resonator. The micro-ring resonator is operable to add a first optical signal at a preselected wavelength received from the first optical add path to the first optical waveguide to travel in a first direction through the first optical waveguide. The micro-ring resonator is further operable to add a second optical signal at the preselected wavelength received from the second optical add path to the first optical waveguide to travel in a second direction through the first optical waveguide opposite to the first direction. There is also provided an optical drop switch, an optical switching apparatus, an optical communications network node and an optical communications network.

An optical switch, comprising: a first optical waveguide, a first optical add path, a second optical add path and a micro-ring resonator. The micro-ring resonator is operable to add a first optical signal at a preselected wavelength received from the first optical add path to the first optical waveguide to travel in a first direction through the first optical waveguide. The micro-ring resonator is further operable to add a second optical signal at the preselected wavelength received from the second optical add path to the first optical waveguide to travel in a second direction through the first optical waveguide opposite to the first direction. There is also provided an optical drop switch, an optical switching apparatus, an optical communications network node and an optical communications network.

10-Gbps client signals (1a) to (1c) which are processed by a 10-Gbps transponder (3a), a 40-Gbps transponder (3b), and a 100-Gbps transponder (3c), respectively, are branched by optical couplers (2a) to (2c) into an M:N switch (40). The M:N switch (40) selects a client signal to be made redundant from the branched client signals (1a) to (1c) and outputs the selected client signal to a redundancy 100-Gbps transponder (50) having 10-Gbps-based client interfaces.

A procedure for transferring wavelengths, and a system that operates in accordance with the procedure. The system comprises at least one network terminal, each including a switch and a controller. A plurality of wavelength sets are applied to the switch. The controller is arranged to operate the switch such that the switch (a) selects at least one wavelength from at least one of the plurality of wavelength sets, based on electrical monitoring at a port module external to the network terminal, and (b) outputs the at least one wavelength to an output of the at least one network terminal.